LOPEC 2015 takes place from the 3rd to the 5th of March this year in Munich and is the International Exhibition and Conference for the Printed Electronics Industry.
At this occasion, Oxford Lasers will present a Scientific Conference Poster on Wednesday the 4th of March, 6pm in the ICM Foyer:
Optimization of laser high speed thin film patterning and transfer (LIFT) of Ag nanoparticle inks for sensor fabrication on flexible substrates, speaker Dr. Emeric Biver, Marie Curie Post Doctoral Fellow.
In this work we present two laser techniques to fabricate electrodes for sensors on flexible substrates: thin film patterning and digital printing. Using a DPSS nanosecond pulsed laser we studied thin film patterning of a fully coated metal layer and the influence of several parameters on the film selective removal (e.g. pulse length, beam shape, polarization direction, incidence angle). We used this technique to print high quality electrodes (Fig. 1a). For high speed printing we used LIFT (laser-induced forward transfer), a versatile, non-contact and high-resolution laser printing technique. The dynamics of the LIFT of silver nanoparticles inks was investigated by time resolved imaging in a μs time scale. We printed long and continuous lines with a DPSS picosecond pulsed laser at both low and high repetition rates (up to 1 MHz) with velocities up to 10 m/s (Fig. 1b).
Laser sintering proved to be reproducible and effective to cure the ink deposited and we obtained low measured resistivities very close to that of bulk metal. After sintering, the printed lines have been used as electrodes for humidity sensors on flexible substrate. We obtained consistent and reproducible changes in resistance (5 – 80 %) and a quick response time.
These processes have wide laser process windows that are fully compatible with industrial laser processing. They can be integrated into an advanced laser digital processing platform which combines laser micro/nano‐patterning with high speed laser printing and sintering of metallic nanoparticle inks with the goal to manufacture high spatial resolution organic sensors.
Figure 1. Example of electrodes fabricated at 500 kH and 10m/s: a) ablated at 390 mJ/cm2 (80 μm between lines and 100 μm line width); b) deposited with LIFT at 74 mJ/cm2 (60 μm between lines and 100 μm line width)
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